Hypervolemia

Hypervolemia, or fluid overload, is an abnormal expansion of the extracellular fluid volume, usually arising from increased sodium and water retention. It commonly presents with edema and signs of systemic or pulmonary congestion and can occur with hypertension and weight gain.

Causes include congestive heart failure, chronic kidney disease, cirrhosis with ascites, nephrotic syndrome, and iatrogenic fluid administration. In many conditions, neurohormonal systems such as the renin-angiotensin-aldosterone system and antidiuretic hormone are inappropriately activated, promoting sodium and water retention.

Pathophysiology involves impaired homeostatic excretion of fluid, leading to expanded intravascular and interstitial volumes. This can raise hydrostatic pressures, causing edema, pulmonary edema, and organ congestion.

Signs and symptoms include peripheral edema (often pitting), jugular venous distension, weight gain, dyspnea, cough, orthopnea, ascites, and, in severe cases, pleural effusions or edema of the liver. Urine output may be reduced if kidney function is impaired.

Diagnosis is clinical and supported by imaging and labs. Assessment includes history, exam for edema and jugular venous pressure, chest radiography or echocardiography to assess heart failure, and blood tests (electrolytes, kidney function, BNP). Sodium level helps distinguish hypervolemia from hyponatremia due to fluid shifts.

Management focuses on treating the underlying cause and reducing fluid overload. Measures include fluid restriction, dietary sodium restriction, and diuretics (typically loop diuretics). In resistant cases, higher-dose diuretics, combination diuretics, or ultrafiltration may be used. Ongoing monitoring of weight, input/output, and electrolytes is essential.

Prognosis depends on the underlying disease; chronic hypervolemia from heart failure or advanced kidney or liver disease is associated with higher morbidity and risk of hospitalization.